Modern day vehicles include numerous components that attain relatively high temperatures during the course of vehicle operation. The engine and the transaxle are two examples of such vehicle components. At elevated temperatures of the engine and transaxle, the losses caused by friction are relatively low resulting in reduced fuel consumption. However, the engine and transaxle lose heat to their surroundings when the vehicle is turned off. Over time, these components slowly cool down and eventually reach equilibrium with the ambient temperature. When the vehicle is subsequently turned on in this cooled down state, the losses due to friction are relatively high, thereby increasing fuel consumption compared to the elevated temperature state.
After the cold start, the engine coolant first needs to warm up before it can provide heat to the vehicle cabin, thereby causing occupant discomfort in winter. Moreover, to satisfy emission requirements for a hybrid electric vehicle (HEV), a cold engine requires the vehicle subsystem controller to keep the engine running regardless of propulsion needs until a prescribed engine temperature is reached. This means the HEV system functionality is not utilized during this time and possible fuel economy gains are not achieved.